In an image processing apparatus equipped with an automatic document feeder (hereinafter, referred to as ADF) for automatically feeding original documents (hereinafter, referred to simply as documents) to an original image reading section, such as a printer, a scanner, a copying machine, and a copying.cndot.facsimile complex apparatus, when the documents are jammed in the ADF or transfer sheets are jammed, a job so-called "recovery" must be carried out. In other words, after the jam is cleared, a certain number of the documents are returned to the set position, so that they are read again.
Japanese Laid-open Patent Application No. 66586/1990 (Tokukaihei No. 2-66586) discloses a "document recovery method", which relates to an invention for the recovery after the jam in the copying machine is cleared. According to this document recovery method, the number of the documents to be returned is computed based on the number of the documents which have been fed and the number of the transfer sheets which have been released. In this document recovery method, the suspended job is controlled based on only one kind of table exhibiting the job state when the jam occurred.
According to the above publication, the recovery of the documents is carried out based on the feeding state of the documents, which is obtained by discovering the current position of the documents using document counters.
More specifically, to obtain the feeding state of the documents, the following counters are provided as the document counters: a pre-feeding counter A for counting the action that a document is transported to a pre-feeding position in the ADF; a feeding counter B for counting the action that the document is transported to a document reading position in the ADF; a released document counter C for counting the action that the document is transported to a document releasing position in the ADF; and a released transfer sheet counter D for counting the action that a transfer sheet having formed thereon a copy image of the corresponding document is released outside of the apparatus.
In other words, it could be described as: when the pre-feeding is completed in the ADF, Pre-feeding Counter A=A+1; when the feeding in the ADF is completed, Pre-feeding Counter A=A-1 and Feeding Counter B=B+1; when the document releasing is completed in the ADF, Feeding Counter B=B-1 and Released Document Counter C=C+1; and when the transfer sheet releasing for the corresponding document is completed, Released Transfer Sheet Counter D=D-1.
Thus, when the transfer sheets are jammed, the number M of the documents to be returned in the SS (Simplex to Simplex) mode is computed as follows:
(1) when the released transfer sheet counter D does not exhibit "0" (zero), that is, when the copying job for all the released documents has not been completed, M=D +A+B; and PA1 (2) when the released transfer sheet counter D exhibits "0" (zero), that is, when the copying job for all the released documents has been completed, M=0.
The number of the documents to be returned is computed from the value of each counter in this manner, and subsequently the recovery of the documents is carried out.
However, in the above conventional document recovery method, the counters provided at portions having different time series count up/down by one to show the state of the documents and transfer sheets, and there may possibly arise inconveniences that one is subtracted from zero, that is, the counter exhibits a count value of "-1".
To be more specific, in case that the copying machine is of the type whose ADF can be opened/closed with respect to the document table at which each document is read, when the copying job is resumed in the ADF mode while a document is remaining on the document table, the copying machine releases that document from the document table as soon as the copying job is resumed. Here, the pre-feeding counter A counts down by one from the initial value "0" (zero), thereby exhibiting a count value of "-1". Since the count value of "-1" equals to FF (hexadecimal digit), there arises a problem that the copying machine issues a wrong instruction, "Please return 255 (FF) documents".
Some types of the known image processing apparatuses are furnished with various kinds of image processing functions. Thus, the image processing apparatuses of these types effect the selected image processing functions to an original image inputted from the original image reading section, and output a processed image from the printer section. Recently, there has been an increasing demand to provide abilities of efficiently processing a large volume of documents in a short time to the image processing apparatuses of these types, and digital copying machines or the like which can meet such a demand have been developed.
Also, some types of the commercialized complex digital copying machines can output, from the printer section, an image inputted from either its own original image reading section or an external device through a facsimile function or a printer function.
High speed, high quality, multi-function, low costs, low power consumption, etc. are basic requirements for these image processing apparatuses. Further, to meet the today's demand, these image processing apparatuses need to have the abilities of immediately and precisely carrying out not only a series of job events from reading an original image to outputting an input image, but also the recovery from a trouble, such as jam recovery.
For example, when the jam occurs in the duplex ADF employed in a digital copying machine while the documents are successively being read, the key factor to improve the work efficiency is whether or not the jam recovery can be carried out smoothly after the jam is cleared.
According to the arrangement of aforementioned Japanese Laid-open Patent Application No. 66586/1990 (Tokukaihei No. 2-66586), the copying machine checks the side (main or back side) of the first document fed when the copying job is resumed, and if the checked side is not the side to be copied next, it automatically flips the document, so that the operator can omit a tedious job of resetting the returned documents in an appropriate order.
More specifically, according to the arrangement of the above publication, the copying machine is furnished with: a document side detecting section for detecting the side of the document set on the platen; a document recovery processing section for comparing the detected side of the document and the document side to be copied next, and for flipping the document if the two sides do not coincide; and a copying job completion judging section for judging whether the copying job for the released document is completed or not. Thus, the copying machine flips the fed document if the side of the document detected when the copying job has resumed does not match with the document side to be copied next, and judges whether the document barge is necessary when the operation of the copying machine is suspended by computing the number of the documents to be returned based on the correlation between the transfer sheets and the documents. Consequently, the above arrangement is effective in that the operator can omit a tedious job of resetting the documents, and that the work efficiency in the jam recovery can be improved.
However, as previously mentioned, not only the abilities of handling a large volume of the documents, but also the abilities of processing an input image from an external device have been increasingly demanded to the image processing apparatus. Thus, to provide an apparatus which can overcome various kinds of troubles arising in any of the available modes, an input image should be processed by more complicated control managing techniques.
In other words, the above publication describes the improvement of the work efficiency in the jam recovery by correlating the transfer sheets to the documents, but fails to disclose an input image management technique which can overcome the troubles occurring with an image inputted from a facsimile machine and a personal computer. Thus, there still remains a problem that once a trouble occurs, the recovery takes a considerable time.
In addition, when a document feeding error occurs in the ADF while a large volume of documents are successively read, or a trouble like the jam occurs in the image output section while the input images processed in several modes are outputted successively, the correlation between the transfer sheets and the documents established up to the occurrence of the error/trouble becomes useless unless the jam recovery is carried out in an accurate manner in the original image reading step and image outputting step. If the correlation becomes useless, the images should be read and processed again, thereby wasting the processing up to the occurrence of the error/trouble. Hence, the conventional managing method has a problem that it can not improve the work efficiency.
Further, a control section for effecting the above managing technique becomes too complicated compared with a case where the above management is not carried out. Thus, to maintain the work efficiency, a high-performance processor and accompanying peripheral circuits are necessary, thereby posing a problem that the resulting apparatus becomes very expensive.